Foot structure for apparatus

ABSTRACT

A foot structure for an apparatus including a bolt member, a slide cup, and a flange member in one embodiment. The bolt member has a first end and a second end. The first end of the bolt member is fixed to the apparatus. The slide cup has at its upper portion a recess for slidably supporting the second end of the bolt member and has at its lower portion a substantially flat lower surface and a rodlike projection projecting downward from a substantially central portion of the lower surface. The flange member has a slide surface with which the lower surface of the slide cup is in slidable contact and a wall surface projecting downward from the slide surface to define an opening area for accommodating the rodlike projection with play. The flange member is mounted on a substantially horizontal floor surface. With this structure, horizontal movement of the rodlike projection of the slide cup is limited within the opening space defined by the wall surface of the flange member, thereby limiting the range of displacement of the apparatus relative to the floor surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a foot structure for anapparatus, and more particularly to an earthquake-resistant footstructure suitable for an electronic apparatus.

2. Description of the Related Art

When installing an electronic apparatus such as a computer in a buildingconstruction, it is important to take measures against an earthquake, soas to minimize falling of the apparatus and damage to the inside of theapparatus due to seismic vibrations. In conventional measures against anearthquake, a foot structure used in installing the apparatus in thebuilding construction, has had emphasis placed on increasing amechanical strength thereof. Recently, however, attention is being givento a vibration isolating technique intended to reduce damage byefficiently converting vibration energy into another form of energy suchas energy of movement.

FIG. 1A shows a conventional foot structure used in installing anapparatus 2 on a floor surface 4. The foot structure shown in FIG. 1Aincludes a bolt member 6 and a slide cup 8. The bolt member 6 has afirst end 6A and a second end 6B. The first end 6A is fixed to theapparatus 2. The slide cup 8 has at its upper portion a recess 8A forslidably supporting the second end 6B of the bolt member 6 and has atits lower portion a lower surface 8B slidable on the floor surface 4.When relatively small seismic vibrations are given to this footstructure, the bolt member 6 horizontally moves within the recess 8A ofthe slide cup 8, so that energy of the seismic vibrations is convertedinto energy of movement (or frictional heat), thus exerting a vibrationisolating effect.

When large seismic vibrations are imparted to this earthquake-resistantfoot structure, and the floor surface 4 is displaced in the direction ofan arrow A as shown in FIG. 1B, not only the bolt member 6 moves withinthe recess 8A of the slide cup 8, but also the slide cup 8 itselfhorizontally slides on the floor surface 4, thereby obtaining a greatvibration isolating effect by relative movement of the bolt member 6 andthe slide cup 8 and relative movement of the slide cup 8 and the floorsurface 4.

Further, another foot structure has been proposed (Japanese PatentLaid-open No. 5-99273). In this foot structure, the recess 8A of theslide cup 8 has a spherical surface, and the second end 6B of the boltmember 6 also has a spherical surface whose radius of curvature issmaller than that of the spherical surface of the recess 8A, therebyeasily restoring the relative positional relation between the boltmember 6 and the slide cup 8 to an original state when seismicvibrations stop.

The conventional foot structure does not have a function of limiting therange of displacement of the apparatus relative to the floor surface.Accordingly, in the case that a earthquake having a large magnitudebeyond expectation occurs for a long period of time, the apparatus movesthus causing collision between the apparatus and another apparatus orwith a wall of the building construction. As a result, each apparatus orthe building construction is damaged. Further, in the case that a man ispresent between the apparatus and the wall, a survival space for the manis lost.

Further, the conventional foot structure does not have a verticalvibration isolating effect to the apparatus. Accordingly, when theapparatus receives vertical seismic vibrations, the bolt member may comeout of the recess of the slide cup, so that the original performance ofthe slide cup cannot be exhibited.

Further, in the case that the floor surface, which is generally expectedto be horizontal and flat is in fact uneven or inclined, there is apossibility of the bolt member escaping from the slide cup in theconventional foot structure, so that the expected vertical vibrationisolating effect cannot be exerted.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a footstructure which can limit the range of displacement of an apparatusrelative to a floor surface.

It is another object of the present invention to provide a footstructure having a vertical vibration isolating effect.

It is a further object of the present invention to provide a footstructure which can prevent the escape of a bolt member from a slidecup.

A first configuration of a foot structure for an apparatus according tothe present invention comprises a bolt member, a slide cup, and a flangemember. The bolt member has a first end and a second end. The first endof the bolt member is fixed to the apparatus. The slide cup has at itsupper portion a recess for slidably supporting the second end of thebolt member and has at its lower portion a substantially flat lowersurface and a rodlike projection projecting downward from asubstantially central portion of the lower surface. The flange memberhas a slide surface with which the lower surface of the slide cup is inslidable contact and a wall surface projecting downward from the slidesurface to define an opening space for accommodating the rodlikeprojection with play. The flange member is mounted on a substantiallyhorizontal floor surface.

According to the first configuration, the slide cup and the flangemember each having a specific shape are adopted, so that horizontalmovement of the rodlike projection of the slide cup is limited withinthe opening space defined by the wall surface of the flange member.Accordingly, the range of displacement of the apparatus relative to thefloor surface can be limited.

In accordance with another aspect of the first configuration accordingto the present invention, there is provided a foot structure for anapparatus, comprising a bolt member having a first end and a second end,said first end being fixed to said apparatus; and a slide cup having atits upper portion a recess for slidably supporting said second end ofsaid bolt member and having at its lower portion a substantially flatlower surface and a rodlike projection accommodated with play in anopening space defined through a slide surface with which said lowersurface is in slidable contact.

A second configuration of a foot structure for an apparatus according tothe present invention comprises a bolt member, a slide cup, and anelastic member. The bolt member has a first end and a second end. Thefirst end of the bolt member is fixed to the apparatus. The slide cuphas at its upper portion a recess for slidably supporting the second endof the bolt member and has at its lower portion a lower surfacecontacting a substantially horizontal floor surface. The elastic memberconnects the apparatus and the floor surface.

According to the second configuration, the elastic member is combinedwith a support structure having the bolt member and the slide cup, sothat horizontal movement of the bolt member relative to the slide cup islimited within the range of elastic deformation of the elastic member.Accordingly, the range of displacement of the apparatus relative to thefloor surface can be limited. Furthermore, by the use of the elasticmember, a vertical vibration isolating effect to the apparatus isproduced, and the escape of the bolt member from the slide cup issuppressed.

In accordance with another aspect of the second configuration accordingto the present invention, there is provided a foot structure for anapparatus, comprising a support member for supporting said apparatus soas to allow oscillation; and an elastic member for connecting saidapparatus and a substantially horizontal floor surface.

A third configuration of a foot structure for an apparatus according tothe present invention comprises a bolt member, biasing means, and aslide cup. The bolt member comprises a first member and a second member.The first member is fixed to the apparatus, and one of the first memberand the second member has a hole for loosely engaging the other. Thebiasing means biases the first member and the second member in oppositedirections. The slide cup has at its upper portion a recess for slidablysupporting the second member and has at its lower portion a lowersurface slidable on a substantially horizontal floor surface.

According to the third configuration, by the use of the bolt membercomprising the first member and the second member and the means forbiasing the first member and the second member in opposite directions, avertical vibration isolating effect to the apparatus is produced.

The above and other objects, features and advantages of the presentinvention and the manner of realizing them will become more apparent,and the invention itself will best be understood from a study of thefollowing description and appended claims with reference to the attacheddrawings showing some preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are sectional views of a foot structure in the relatedart;

FIG. 2 is a perspective view showing a form of installation of anelectronic apparatus to which the present invention is applicable;

FIG. 3 is a sectional view of a foot structure showing a first preferredembodiment of the present invention;

FIG. 4 is a sectional view of a foot structure showing a secondpreferred embodiment of the present invention;

FIG. 5 is a sectional view of a foot structure showing a third preferredembodiment of the present invention;

FIG. 6 is a sectional view of a foot structure showing a fourthpreferred embodiment of the present invention;

FIG. 7 is a sectional view of a foot structure showing a fifth preferredembodiment of the present invention;

FIG. 8 is a sectional view of a foot structure showing a sixth preferredembodiment of the present invention;

FIG. 9 is a sectional view of a foot structure showing a seventhpreferred embodiment of the present invention;

FIGS. 10A and 10B are sectional views of a foot structure showing aneighth preferred embodiment of the present invention;

FIG. 11 is a sectional view of a foot structure showing a ninthpreferred embodiment of the present invention;

FIG. 12 is a sectional view of a foot structure showing a tenthpreferred embodiment of the present invention;

FIG. 13 is a sectional view of a foot structure showing an eleventhpreferred embodiment of the present invention;

FIG. 14 is a sectional view of a foot structure showing a twelfthpreferred embodiment of the present invention; and

FIG. 15 is a sectional view of a foot structure showing a thirteenthpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a perspective view showing a form of installation of anelectronic apparatus to which the present invention is applicable. Inthe following description, substantially the same parts will be denotedby the same reference numerals, and the description thereof may beomitted to avoid repetition.

There is defined a room used as a computer room or the like by a floor14 and walls 16 of a building construction 12. A plurality of freeaccess floors 20 are entirely laid over the floor 14 through supports18, which are spread out substantially horizontally, so that an actualfloor surface in this room is provided by these free access floors 20.Reference numeral 22 represents an electronic apparatus incorporatingone or more electronic devices 23 such as computer units. Eachelectronic device 23 has an electronic circuit having a possibility ofmalfunction due to vibrations, for example. The electronic apparatus 22is installed at its four lower corners on the free access floors 20 bymeans of foot structures 24 according to the present invention.

Cables 28 of the electronic apparatus 22 extend through an opening 26formed through a joint portion of the free access floors 20 or throughone of the free access floors 20 into a space defined between the freeaccess floors 20 and the floor 14 of the building construction 12. Bythe use of the free access floors 20, scattering of the cables 28 in theroom can be prevented, and the degree of freedom of installation form ofthe electronic apparatus 22 becomes large.

FIG. 3 is a sectional view of a foot structure showing a first preferredembodiment of the present invention. More specifically, FIG. 3 shows asectional configuration of each of the foot structures 24 shown in FIG.2. Each foot structure 24 includes a bolt member 30, a slide cup 32, aflange member 34, and a cover 36 (not shown in the other figures)detachably mounted on the bolt member 30 and the slide cup 32 to coverthe slide cup 32.

The bolt member 30 has a first end 30A and a second end 30B respectivelycorresponding to an upper portion and a lower portion of the bolt member30. The upper portion corresponding to the first end 30A of the boltmember 30 is formed with a threaded portion 30C. The bolt member 30 isfixed at the first end 30A to the electronic apparatus 22 by threadedlyengaging the threaded portion 30C with a nut (not shown) formed on theinner surface of a housing of the electronic apparatus 22 or an insidenut (not shown) provided in the electronic apparatus 22 and tighteningeither nut to an outside nut 38. By rotating the bolt member 30 in aloosened condition of the outside nut 38 to thereby vertically advanceor retract the bolt member 30, the projecting length of the bolt member30 from the bottom surface of the electronic apparatus 22 can beadjusted to thereby adjust the support height of the electronicapparatus 22.

The slide cup 32 has at its upper portion a recess 32A for slidablysupporting the second end 30B of the bolt member 30, and has at itslower portion a substantially flat lower surface 32B and a rodlikeprojection 32C projecting downward from a substantially central portionof the lower surface 32B.

The flange member 34 has a substantially horizontal slide surface 34Awith which the lower surface 32B of the slide cup 32 is in slidablecontact and a wall surface 34B projecting downward from the slidesurface 34A to define an opening space 40 for accommodating the rodlikeprojection 32C with play.

More specifically, the slide cup 32 comprises a cup body 44 having anannular projection (wall portion) 42 for providing the recess 32A and aliner 46 provided on the bottom surface of the cup body 44 except therodlike projection 32C. The lower surface 32B of the slide cup 32 isprovided by the liner 46. The rodlike projection 32C is formedintegrally with the cup body 44, thereby ensuring a sufficient strength.

More specifically, the flange member 34 comprises a platelike portion 48for providing the slide surface 34A and a cylindrical portion 50 forproviding the wall surface 34B. The platelike portion 48 is adisk-shaped portion having an outer diameter larger than the outerdiameter of the slide cup 32 and an inner diameter smaller than theouter diameter of the slide cup 32. The platelike portion 48 and thecylindrical portion 50 are formed integrally with each other.

In this preferred embodiment, the upper surface 20A of each free accessfloor 20 constitutes a floor surface, so that the following structure isprovided to mount the flange member 34 on the floor surface 20A. Thatis, the free access floor 20 has a hole 20B having a diameter largerthan the outer diameter of the cylindrical portion 50 and smaller thanthe outer diameter of the platelike portion 48. The cylindrical portion50 is inserted through the hole 20B, so that the flange member 34 ispositioned with respect to the free access floor 20. With thisstructure, the flange member 34 can be mounted on the floor surface 20Aonly by a simple operation of inserting the cylindrical portion 50 intothe hole 20B of the free access floor 20.

It is now assumed that an earthquake has occurred to cause vibrations ofthe free access floor 20 in a horizontal direction (lateral direction asviewed in FIG. 3). In the case that the amplitude of the seismicvibrations is relatively small, the second end 30B of the bolt member 30slides relative to the recess 32A of the slide cup 32, thereby exertinga horizontal vibration isolating effect. When the amplitude of theseismic vibrations becomes large to cause collision of the bolt member30 with the wall portion 42 of the slide cup 32, the slide cup 32 slidesrelative to the slide surface 34A of the flange member 34, therebyexerting a horizontal vibration isolating effect. The allowable range ofrelative sliding of the slide cup 32 in this case is limited within apredetermined circular area because the rodlike projection 32C isaccommodated in the opening space 40 with play. Thus, according to thispreferred embodiment, the range of displacement of the electronicapparatus 22 relative to the floor surface 20A is limited, so that thereis no possibility of collision of the electronic apparatus 22 with thewalls 16 or the like in the building construction 12 (see FIG. 2) uponoccurrence of a great earthquake.

As mentioned above, the bolt member 30 starts to slide relative to theslide cup 32 before the slide cup 32 starts to slide relative to theflange member 34 according to the amplitude of the seismic vibrations.To effect this operation, a first friction coefficient between thesecond end 30B of the bolt member 30 and the recess 32A is set smallerthan a second friction coefficient between the lower surface 32B of theslide cup 32 and the slide surface 34A of the flange member 34 in thispreferred embodiment. More specifically, the bolt member 30 is formed ofmetal such as steel, and the second end 30B has a spherical surface.

The radius of curvature of the second end 30B of the bolt member 30 isin the range of preferably 30 mm to 40 mm, because if the radius ofcurvature is too small, the second end 30B becomes prone to wear,whereas if the radius of curvature is too large, the first frictioncoefficient becomes too large to result in a problem that a desiredoperation cannot be obtained.

Owing to the material of the bolt member 30 and the shape of the secondend 30B as mentioned above, a relatively small value of the firstfriction coefficient can be obtained. A target value of the firstfriction coefficient is 0.1, for example.

A target value of the second friction coefficient is set to 0.2, forexample. To this end, a self-lubricating material such as Teflon(registered trademark of DuPont) and nylon is adopted as the material ofthe liner 46. Further, metal such as steel is adopted as the material ofthe flange member 34, and the slide surface 34A of the flange member 34is flat.

In this preferred embodiment, the recess 32A of the slide cup 32 has ashape such that the recess 32A is deepest at its central portioncorresponding to the rodlike projection 32C and gradually shallowed fromthe central portion toward the radially outermost portion. A targetvalue of the angle of slant of the recess 32A is 1°, for example. Owingto such a shape of the recess 32A, the bolt member 30 can be easilyreturned to the deepest central portion of the recess 32A by slightseismic vibrations occurring prior to the end of an earthquake.

The cover 36 for covering the slide cup 32 is formed of a flexiblematerial such as rubber. The cover 36 has at its substantially centralportion a hole for insertion of the bolt member 30 in a sealedcondition. Further, the outer circumference of the cover 36 is in tightcontact with the outer side surface of the slide cup 32. To maintain aninserted condition of the bolt member 30 through the hole of the cover36, the bolt member 30 has two large-diameter portions 30D and 30Ebetween the second end 30B and the threaded portion 30C. Thus, there isdefined an enclosed space by the cover 36 and the slide cup 32.Accordingly, the first friction coefficient can be easily maintained ata stable value. In other words, it is possible to prevent ageddeterioration of the first friction coefficient due to deposition ofdust on the recess 32A.

In this preferred embodiment, an elastic ring 52 formed of rubber or thelike is engaged with the bolt member 30 in the vicinity of the secondend 30B, so as to absorb shock when the bolt member 30 is about tocollide with the wall portion 42 of the slide cup 32. Accordingly,malfunction of the electronic devices 23 (see FIG. 2) due to applicationof undesired shock to the electronic apparatus 22 can be prevented. Forexample, it is possible to prevent malfunction due to tracking error ina mechanical recording device such as a hard disk drive or noise causedby movement of a mechanical contact such as a connector provided on aprinted board.

While the flange member 34 is simply fitted with the free access floor20 in the preferred embodiment shown in FIG. 3, the flange member 34 maybe fixed to the free access floor 20 by means of screws or adhesive forthe purpose of more firmly mounting the flange member 34 on the floorsurface 20A.

FIG. 4 is a sectional view of a foot structure showing a secondpreferred embodiment of the present invention. In contrast with the footstructure shown in FIG. 3, the foot structure of this preferredembodiment is characterized in that it further includes a plate member54' fixed to the lower end of the rodlike projection 32C of the slidecup 32. The plate member 54' is fixed to the rodlike projection 32C bymeans of a screw 56. The plate member 54' is formed from a steel plate,for example, and has a diameter larger than the diameter of the hole 20Bof the free access floor 20.

By the addition of the plate member 54', the placement of the flangemember 34 to the free access floor 20 can be made stable. That is, sincethe plate member 54' is larger in diameter than the hole 20B of the freeaccess floor 20, it is possible to obtain a structure such that the freeaccess floor 20 is sandwiched between the plate member 54' and theplatelike portion 48 of the flange member 34. As a result, even when therodlike projection 32C of the slide cup 32 comes into collision with thecylindrical portion 50 of the flange member 34 upon occurrence of anearthquake, the escape of the bolt member 30 from the slide cup 32 dueto flying of the slide cup 32 caused by such collision or the like.

Furthermore, according to this structure, there is no possibility ofdisengagement of the flange member 34 from the free access floor 20 evenwithout the use of screws or the like for fixing the flange member 34 tothe free access floor 20. Preferably, the lower end of the cylindricalportion 50 of the flange member 34 slightly projects from the lowersurface of the free access floor 20 to such a degree that the platemember 54' does not contact the lower surface of the free access floor20.

For the purpose of facilitating horizontal movement of the slide cup 32relative to the flange member 34 upon occurrence of an earthquake, alubricant or an equivalent member may be applied or attached to thelower end of the cylindrical portion 50 of the flange member 34 or theupper surface of the plate member 54'.

FIG. 5 is a sectional view of a foot structure showing a third preferredembodiment of the present invention. In contrast with the foot structureshown in FIG. 4, the foot structure of this preferred embodiment ischaracterized in that a single (ringlike) or plural elastic members 58are interposed between the platelike portion 48 of the flange member 34and the floor surface 20A, and a single (ringlike) or plural elasticmembers 60 are interposed between the lower surface of the free accessfloor 20 and the plate member 54'. The elastic members 58 and 60 areformed of rubber, for example. FIG. 5 shows that the elastic members 58are in a contracted condition given by a compressive force and theelastic members 60 are in a stretched condition given by a tensileforce. With this structure, the flange member 34 is allowed tovertically move relative to the free access floor 20 upon occurrence ofan earthquake, thereby producing a vertical vibration isolating effectto the electronic apparatus 22.

According to the third preferred embodiment shown in FIG. 5, it ispossible to provide a foot structure which can limit the range ofdisplacement of the apparatus relative to the floor surface and canexert a vertical vibration isolating effect to the apparatus.

FIG. 6 is a sectional view of a foot structure showing a fourthpreferred embodiment of the present invention. In contrast with the footstructure shown in FIG. 3, the foot structure of this preferredembodiment is characterized in that it further includes an elastic sheet62 attached to the wall surface 34B of the flange member 34. The elasticsheet 62 is formed of rubber, for example. According to this preferredembodiment, the elastic sheet 62 functions to absorb shock when therodlike projection 32C of the slide cup 32 is about to collide with thewall surface 34B of the flange member 34 upon occurrence of anearthquake. Accordingly, the horizontal vibration isolating effect canbe enhanced, and malfunction or the like of the electronic devices 23(see FIG. 2) incorporated in the electronic apparatus 22 can beprevented.

FIG. 7 is a sectional view of a foot structure showing a fifth preferredembodiment of the present invention. The foot structure of thispreferred embodiment is characterized in that an elastic block 64 formedof rubber or the like is used in place of the elastic sheet 62 shown inFIG. 6. The elastic block 64 is interposed between the wall surface 34Bof the flange member 34 and the rodlike projection 32C of the slide cup32, and is fixed therebetween by adhesion, for example. According tothis foot structure as similar to the foot structure shown in FIG. 6,the elastic block 64 functions to absorb shock when the rodlikeprojection 32C of the slide cup 32 is about to collide with the wallsurface 34B of the flange member 34. Accordingly, the horizontalvibration isolating effect can be enhanced, and malfunction or the likeof the electronic devices 23 incorporated in the electronic apparatus 22can be prevented.

In the preferred embodiment shown in FIG. 6 or 7, it is preferable toselect a material having a small elastic coefficient as the material ofthe elastic sheet 62 or the elastic block 64, so as to damp an impactforce proportional to a velocity change when the rodlike projection 32Cof the slide cup 32 is about to collide with the wall surface 34B of theflange member 34.

All of the above-mentioned preferred embodiments are included in thefirst configuration of the foot structure of the present invention.

There will now be described two preferred embodiments included in thesecond configuration of the foot structure of the present invention withreference to FIGS. 8 and 9.

FIG. 8 is a sectional view of a foot structure showing a sixth preferredembodiment of the present invention. This foot structure includes a boltmember 30 whose first end 30A is fixed to the electronic apparatus 22, aslide cup 32' having a recess 32A for slidably supporting a second end30B of the bolt member 30, and a solid cylindrical elastic member 66 forconnecting the electronic apparatus 22 and the floor surface 20A.

In this preferred embodiment, the slide cup 32' has a form such that therodlike projection 32C has been removed from the slide cup 32 in thefirst preferred embodiment shown in FIG. 3. In association therewith, aliner 46 is provided on the entirety of the lower surface of the cupbody 44. As a result, a substantially flat lower surface 32B' of theslide cup 32' is provided by the liner 46, and the slide cup 32' isslidable on the floor surface 20A.

The elastic member 66 is fixed to the electronic apparatus 22 and thefloor surface 20A at a position different from the position of the boltmember 30. More specifically, the elastic member 66 is formed of rubberor the like, and brackets 68 and 70 are provided at the upper and lowerends of the elastic member 66. The bracket 68 is fixed through a base 72to the electronic apparatus 22 by means of bolts 74, and the bracket 70is fixed through a base 76 to the floor surface 20A by means of bolts78.

The operation of the bolt member 30 and the slide cup 32' in thispreferred embodiment should be understandable according to the relatedart shown in FIGS. 1A and 1B, so the description thereof will be omittedherein. According to this preferred embodiment, the electronic apparatus22 and the floor surface 20A are connected by the elastic member 66, sothat the displacement of the electronic apparatus 22 relative to thefloor surface 20A is limited within the allowable range of elasticdeformation of the elastic member 66, thus achieving one of the objectsof the present invention. Further, by the use of the elastic member 66,a vertical vibration isolating effect to the electronic apparatus 22 isproduced, and the escape of the bolt member 30 from the slide cup 32' isprevented. Additionally, the bolt member 30 and the slide cup 32' can beselected from conventional ones, so that the second configuration of thefoot structure of the present invention can be easily provided.

FIG. 9 is a sectional view of a foot structure showing a seventhpreferred embodiment of the present invention. In contrast with thepreferred embodiment shown in FIG. 8 employing the solid cylindricalelastic member 66 provided at a position different from the position ofthe bolt member 30, the preferred embodiment shown in FIG. 9 ischaracterized in that a hollow cylindrical elastic member 66' forconnecting the electronic apparatus 22 and the floor surface 20A isprovided so as to surround the bolt member 30. Further, a slide cup 32"is fixed to the floor surface 20A by means of bolts 79.

More specifically, the slide cup 32" has a form such that the liner 46has been removed from the slide cup 32' shown in FIG. 8, that is, theslide cup 32" is identical with the cup body 44 itself. Such a form ofthe slide cup 32" provides a recess 32A for slidably supporting thesecond end 30B of the bolt member 30. The lower end of the hollowcylindrical elastic member 66' is fixed to the slide cup 32" at its wallportion 42 by means of bolts 81, and the upper end of the elastic member66' is fixed to the electronic apparatus 22 by means of bolts 83. Thus,the elastic member 66' is fixed to the slide cup 32" and the electronicapparatus 22, thereby defining an enclosed space inside the elasticmember 66' to prevent deposition of dust on the recess 32A causinghindrance against a desired operation.

According to this preferred embodiment, the displacement of theelectronic apparatus 22 to the floor surface 20A is limited within theallowable range of elastic deformation of the elastic member 66',thereby achieving one of the objects of the present invention. Further,the electronic apparatus 22 and the slide cup 32" are connected by theelastic member 66', and the slide cup 32" is fixed to the floor surface20A. Accordingly, a vertical vibration isolating effect to theelectronic apparatus 22 upon occurrence of an earthquake is produced.Further, there is no possibility of the escape of the bolt member 30from the slide cup 32" upon occurrence of an earthquake.

In the preferred embodiment shown in FIG. 9, the elastic member 66' isformed of rubber, so that the enclosed space inside the elastic member66' can be reliably sealed.

The second configuration of the foot structure of the present inventionis not limited to the preferred embodiment shown in FIG. 8 or thepreferred embodiment shown in FIG. 9. For example, a plurality ofplatelike or rodlike elastic members may be used to connect theelectronic apparatus 22 and the slide cup 32" on the basis of thepreferred embodiment shown in FIG. 9. Although a sealing effect cannotbe obtained by the elastic members in this case, the other effects aresimilar to those of the preferred embodiment shown in FIG. 9.

Some preferred embodiments included in the third configuration of thefoot structure of the present invention will now be described.

FIGS. 10A and 10B are sectional views of a foot structure showing aneighth preferred embodiment of the present invention. FIG. 10B shows acondition where the foot structure is mounted to the electronicapparatus 22, and FIG. 10A shows a condition where the foot structurehas been removed from the electronic apparatus 22. Unlike the previouspreferred embodiments, this preferred embodiment employs a bolt member80 composed of a first member 82 and a second member 84 as separatemembers.

The first member 82 has an upper end 82A and a threaded portion 82Brespectively corresponding to the first end 30A and the threaded portion30C of the bolt member 30 (see FIG. 3, for example). The second member84 has a large-diameter portion 84A and a lower end 84B respectivelycorresponding to the large-diameter portion 30E and the second end 30Bof the bolt member 30. The first member 82 further has a hole 82C forloosely engaging a part of the second member 84 which is substantiallysolid cylindrical. The lower end 84B of the second member 84 is slidablysupported by a recess 32A of a slide cup 32' similar to that in thesixth preferred embodiment shown in FIG. 8. The lower surface 32B' ofthe slide cup 32' is slidable relative to the floor surface 20A. Thelower surface 32B' is provided by a liner 46. A rubber block 86 having asubstantially spherical shape, for example, is interposed between thetop surface in the hole 82C of the first member 82 and the upper end 84Cof the second member 84, so as to bias the first member 82 and thesecond member 84 in opposite directions.

When the foot structure of this preferred embodiment is mounted to theelectronic apparatus 22, the rubber block 86 is elastically deformed bythe weight of the electronic apparatus 22 to become a compressedcondition shown in FIG. 10B. On the other hand, when this foot structureis demounted from the electronic apparatus 22, the rubber block 86restores its original shape as shown in FIG. 10A.

In contrast with the related art shown in FIGS. 1A and 1B, thispreferred embodiment has the following feature. That is, since the firstmember 82 and the second member 84 constituting the bolt member 80 arebiased in opposite directions by the rubber block 86, a verticalvibration isolating effect to the electronic apparatus 22 in addition toa horizontal vibration isolating effect thereto can be produced.Accordingly, even when the electronic apparatus 22 is largely vibratedin the vertical direction, the bolt member 80 is prevented from jumpingthe wall portion 42 because the second member 84 is pressed against theslide cup 32' by the rubber block 86. Thus, according to this preferredembodiment, one of the objects of the present invention can be achieved.

FIG. 11 is a sectional view of a foot structure showing a ninthpreferred embodiment of the present invention. This preferred embodimentemploys an air spring provided by the air charged in the hole 82C inplace of the rubber block 86 shown in FIG. 10. More specifically, thebolt member in this preferred embodiment is composed of a first member82' and a second member 84'. The first member 82' has an air passage 82Dfor making communication of the hole 82C and the outside and a valve 82Efor discharging excess air from the hole 82C through the air passage 82Dor supplying a lacking amount of air into the hole 82C through the airpassage 82D. The second member 84' is formed at its upper portion with ahole 84D opening to the upper end 84C' for the purpose of enlarging thesubstantial volume of the air spring. Further, to prevent air leakagefrom the hole 82C of the first member 82', a rubber ring 88 is fittedwith an annular groove formed on the cylindrical surface of the hole82C, and the second member 84' is inserted into the center hole of therubber ring 88.

According to this preferred embodiment, the first member 82' and thesecond member 84' are biased in opposite directions by the air spring.Accordingly, a vertical vibration isolating effect can be produced assimilarly to the preferred embodiment shown in FIGS. 10A and 10B. Inparticular, by the use of the air spring, air pressure inside the hole82C can be adjusted by the valve 82E, thereby easily obtaining a desiredbiasing force. Further, since the hole 84D is formed in the secondmember 84' to enlarge the substantial volume of the air spring, the airspring for providing a required biasing force can be reduced in size,and a small-sized foot structure can therefore be provided.

FIG. 12 is a sectional view of a foot structure showing a tenthpreferred embodiment of the present invention. In contrast with the footstructure shown in FIGS. 10A and 10B, the foot structure of thispreferred embodiment is characterized in that a plurality of steel balls90 are additionally provided in the hole 82C of the first member 82. Asecond member 84" having a plurality of recesses for respectivelyreceiving the steel balls 90 at their substantially half portions isused to prevent falling of the steel balls 90. Each steel ball 90 isallowed to roll between the cylindrical surface of the hole 82C of thefirst member 82 and the inside surface of the corresponding recess ofthe second member 84", thereby reducing friction between the firstmember 82 and the second member 84". As a result, the first member 82can be moved vertically smoothly relative to the second member 84" uponoccurrence of an earthquake.

FIG. 13 is a sectional view of a foot structure showing an eleventhpreferred embodiment of the present invention. In contrast with the footstructure shown in FIGS. 10A and 10B, the foot structure of thispreferred embodiment is characterized in that it further includes meansfor limiting the range of relative displacement of a first member 82 anda second member 84'". More specifically, the second member 84'" has alarge-diameter portion 84E having a diameter slightly smaller than thediameter of the hole 82C of the first member 82. Further, a ring 92having a circular hole smaller in diameter than the large-diameterportion 84E of the second member 84'" and larger in diameter than theother portion of the second member 84'" is fixed to the lower end of thefirst member 82 by means of bolts 94.

With this structure, the upper limit of vertical movement of the secondmember 84'" is defined by the allowable range of elastic deformation ofthe rubber block 86, and the lower limit of the vertical movement isdefined by the abutment of the lower end of the large-diameter portion84E against the ring 92. Thus, the range of vertical displacement of thesecond member 84'" is limited to thereby prevent the escape of thesecond member 84'" from the first member 82. Further, since the diameterof the large-diameter portion 84E is slightly smaller than the diameterof the hole 82C of the first member 82, the second member 84'" can bevertically moved in the hole 82C with almost no play, thereby allowingstable supporting of the electronic apparatus 22.

FIG. 14 is a sectional view of a foot structure showing a twelfthpreferred embodiment of the present invention. In contrast with the footstructure shown in FIG. 13, the foot structure of this preferredembodiment is characterized in that it further includes a damping rubberring 96 interposed between the lower end of the large-diameter portion84E of the second member 84'" and the ring 92. With this structure, thedamping rubber ring 96 functions to absorb an impact force when thelarge-diameter portion 84E of the second member 84'" is about to collidewith the ring 92. Therefore, the shock is hardly applied to theelectronic apparatus 22, and it is possible to prevent malfunction orthe like of the electronic apparatus 22 when the vertical vibrationisolating effect is exerted upon occurrence of an earthquake. Thedamping rubber ring 96 may have a small elastic coefficient so as tosufficiently damp the impact force.

While the first member has the hole for loosely engaging the secondmember in each preferred embodiment according to the third configurationof the present invention, the second member may have a hole for looselyengaging the first member.

FIG. 15 is a sectional view of a foot structure showing a thirteenthpreferred embodiment of the present invention. In contrast with the footstructure shown in FIGS. 10A and 10B wherein the rubber block 86 asbiasing means is provided in the bolt member 80 to produce a verticalvibration isolating effect, the foot structure of this preferredembodiment is characterized in that means for producing a verticalvibration isolating effect is provided on the floor side.

More specifically, the foot structure shown in FIG. 15 includes the boltmember 30 shown in FIG. 3, a slide cup 32'", and a flange member 34'.The slide cup 32'" has a configuration such that the liner 46 has beenremoved from the slide cup 32 shown in FIG. 3. Further, in contrast withthe flange member 34 shown in FIG. 3, the flange member 34' ischaracterized in that a cylindrical portion 50' is closed at its lowerend. A rubber ring 98 is interposed between the lower surface of the cupbody 44 of the slide cup 32'" and the platelike portion 48 of the flangemember 34', and a rubber block 100 is interposed between the lower endof the rodlike projection 32C of the slide cup 32'" and the bottom ofthe cylindrical portion 50' of the flange member 34'. FIG. 15 shows acondition where the rubber ring 98 and the rubber block 100 arecompressed by the weight of the electronic apparatus 22.

By the provision of the rubber ring 98 and the rubber block 100, avertical vibration isolating effect to the electronic apparatus 22 canbe produced.

The present invention may be embodied by combining two or more of theabove-mentioned preferred embodiments.

As described above, according to the first, second, or thirdconfiguration of the present invention, it is possible to obtain atleast one of the first advantage that the range of displacement of theapparatus relative to the floor surface can be limited, the secondadvantage that the vertical vibration isolating effect to the apparatuscan be produced, and the third advantage that the escape of the boltmember from the slide cup can be suppressed.

The present invention is not limited to the details of the abovedescribed preferred embodiments. The scope of the invention is definedby the appended claims and all changes and modifications as fall withinthe equivalence of the scope of the claims are therefore to be embracedby the invention.

What is claimed is:
 1. A foot structure for an apparatus, comprising:abolt member having a first end and a second end, said first end capableof being fixed to said apparatus; and a slide cup having at an upperportion thereof a recess for slidably supporting said second end of saidbolt member and having at a lower portion thereof a substantially flatlower surface and a rodlike projection accommodated with play in anopening space defined through a slide surface with which said lowersurface is in slidable contact whereby said second end of said boltmember is adapted to move within said slide cup within an amplituderange and whereupon when said bolt member contacts with a wall of saidslide cup said slide cup is adapted to move relative to said slidesurface within a range defined by said rodlike projection and saidopening space.
 2. A foot structure according to claim 1, furthercomprising a flange member mounted on a substantially horizontal floorsurface, said flange member having said slide surface and a wall surfaceprojecting downward from said slide surface to define said openingspace.
 3. A foot structure according to claim 2, further comprising aplate member fixed to said rodlike projection for holding said flangemember in cooperation with said slide cup, whereby the contact betweensaid lower surface of said slide cup and said slide surface of saidflange member is stably maintained.
 4. A foot structure according toclaim 3, wherein said floor surface is provided by a free access floorspaced from a floor of a building construction, said foot structurefurther comprising a first elastic member interposed between a platelikeportion of said flange member and an upper surface of said free accessfloor and a second elastic member interposed between said plate memberand a lower surface of said free access floor.
 5. A foot structureaccording to claim 2, further comprising an elastic sheet attached tosaid wall surface of said flange member for absorbing shock when saidrodlike projection is about to contact said wall surface.
 6. A footstructure according to claim 2, further comprising an elastic blockinterposed between said wall surface of said flange member and saidrodlike projection for absorbing shock when said rodlike projection isabout to contact said wall surface.
 7. An electronic apparatuscomprising:a housing for accommodating an electronic circuit; a boltmember having a first end and a second end, said first end being fixedto said housing; a slide cup having at an upper portion thereof a recessfor slidably supporting said second end of said bolt member and havingat a lower portion thereof a substantially flat lower surface and arodlike projection projecting downward from a substantially centralportion of said lower surface; and a flange member mounted on asubstantially horizontal floor surface, said flange member having aslide surface with which said lower surface of said slide cup is inslidable contact and a wall surface projecting downward from said slidesurface to define an opening space for accommodating said rodlikeprojection with play whereby said second end of said bolt member isadapted to move within said slide cup within an amplitude range andwhereupon when said bolt member contacts with a wall of said slide cupsaid slide cup is adapted to move relative to said slide surface withina range defined by said rodlike projection and said opening space.
 8. Anelectronic apparatus comprising:a housing for accommodating anelectronic circuit; a bolt member having a first end and a second end,said first end being fixed to said housing; and a slide cup having at anupper portion thereof a recess for slidably supporting said second endof said bolt member and having at a lower portion thereof asubstantially flat lower surface and a rodlike projection accommodatedwith play in an opening space defined through a slide surface with whichsaid lower surface is in slidable contact whereby said second end ofsaid bolt member is adapted to move within said slide cup within anamplitude range and whereupon when said bolt member contacts with a wallof said slide cup said slide cup is adapted to move relative to saidslide surface within a range defined by said rodlike projection and saidopening space.